Abstract
The filamentous 'Pf' bacteriophages of Pseudomonas aeruginosa play roles in biofilm formation and virulence, but mechanisms governing Pf prophage activation in biofilms are unclear. Here, we identify a prophage regulatory module, KKP (kinase-kinase-phosphatase), that controls virion production of co-resident Pf prophages and mediates host defense against diverse lytic phages. KKP consists of Ser/Thr kinases PfkA and PfkB, and phosphatase PfpC. The kinases have multiple host targets, one of which is MvaU, a host nucleoid-binding protein and known prophage-silencing factor. Characterization of KKP deletion and overexpression strains with transcriptional, protein-level and prophage-based approaches indicates that shifts in the balance between kinase and phosphatase activities regulate phage production by controlling MvaU phosphorylation. In addition, KKP acts as a tripartite toxin-antitoxin system that provides defense against some lytic phages. A conserved lytic phage replication protein inhibits the KKP phosphatase PfpC, stimulating toxic kinase activity and blocking lytic phage production. Thus, KKP represents a phosphorylation-based mechanism for prophage regulation and antiphage defense. The conservation of KKP gene clusters in >1000 diverse temperate prophages suggests that integrated control of temperate and lytic phage infection by KKP-like regulatory modules may play a widespread role in shaping host cell physiology.